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Biomedical subjects

M Galanski

Publications and source records attributed to M Galanski.

At least 19 recordsLinked to original sources
PubMed1992

Colour Doppler ultrasound assessment of arteriovenous haemodialysis fistulas.

Satisfactory function of the arteriovenous fistula (AVF) is essential for adequate haemodialysis in patients with chronic renal failure. Existing methods to assess AVF function are imprecise (eg, clinical examination) or invasive (eg, angiography). We assessed the value of colour flow-doppler ultrasound (CFDU) in the investigation of clinically suspected AVF dysfunction. 51 patients with suspected impairment of AVF function were studied by CFDU, and 28 also underwent angiography. The findings were compared with the reference standard of the findings at reoperation. CFDU showed AVF stenoses in 18 patients, which were all confirmed at reoperation; the results of angiography in 13 of these 18 patients showed complete agreement with the findings of CFDU and surgery. CFDU showed partial or complete AVF thrombosis in 33 patients, confirmed in all patients at reoperation; 15 patients also underwent angiography, and thrombi were not found in 6 (in 4 because of technical failure). 7 patients had aneurysms on CFDU that were confirmed by surgery in all patients and by angiography in 2 of the 3 patients studied. CFDU enables reliable non-invasive assessment of AVF morphology and function and may become the procedure of choice for AVF assessment in patients with suspected AVF abnormalities.

Adult↗
PubMed1992

[The visibility of a central venous catheter using digital luminescence radiography in intensive care radiology].

The aim of the following study was to assess the impact of dose alterations on the detection of catheters. We compared the performance of well-exposed conventional and digital portable chest radiographs in the detection of thin catheters and tested the influences of dose alterations. Portable chest radiographs of 20 patients were obtained with conventional film/screen (FR) and with storage phosphors at 50% (SRL), 100% (SRN), and 250% (SRH) of the conventionally required exposure dose. The region of the mediastinum was subdivided into an average of 18 fields, 50% of which were superimposed with thin catheter segments. ROC analysis of 11,600 observations by 8 readers found only SRH equivalent to FR in catheter visualisation. Performance decreased significantly with SRN and SRL. Detection of low contrast catheters was found to be significantly decreased in storage phosphor radiographs obtained with standard exposure dose. A dose reduction is not feasible with current equipment if performance equivalent to conventional radiography is to be achieved.

Catheterization, Central Venous↗
PubMed1992

Impact of hard-copy size on observer performance in digital chest radiography.

To determine the impact of reduced hard-copy size on diagnostic performance of digital radiography, screen-film chest radiographs were compared with isodose digital storage phosphor radiographs in the detection of simulated nodules, fine pulmonary lines, and micronodular opacities superimposed on the chests of 10 healthy volunteers. Digital radiographs were laser-printed in a full-size conventional format and in image lengths of two-thirds, one-half, and five-elevenths of the conventional format. Eighteen thousand observations by eight radiologists were analyzed by use of receiver operating characteristics. The detectability of lines and micronodular opacities decreased with declining image format size. In the detection of micronodular opacities, only the nearly full-size digital images were equivalent to conventional images. In the detection of linear opacities, reduction of image length by one-half or more reduced performance (analysis of variance, P less than .05). Only for the detection of nodules was no major difference found.

Humans↗
PubMed1992

[Chemoembolization of hepatocellular carcinoma in cases of isolated liver involvement].

Chemoembolization is an effective treatment for hepatocellular carcinoma, giving results equally as good as surgical therapy for T2 tumours. Survival can be prolonged and side-effects can be reduced by combining Lipiodol and Gelfoam for chemoembolization, employing a modified technique, with repeated procedures, and using appropriate follow-up treatment. The toxicity of the procedure is acceptable, but it requires supportive therapy necessitating an intense interdisciplinary co-operation.

Aged↗
PubMed1992

[The x-ray clinical picture and evaluation criteria of implantable cardioverter-defibrillator systems].

Since the first implantation of an automatic cardioverter defibrillator (ICD) in February 1980, the therapy of ventricular tachyarrhythmia has been changed drastically. The original therapy with antiarrhythmic agents has been increasingly replaced by the implantation of the ICD. The radiologist should be aware of the different types of ICDs and their normal appearance, because thorax radiography is often used during regular routine follow-up of the ICD system. The different types of ICDs, their normal radiological appearances, the indications and the implantation technique are discussed in the present study. The radiologist has to interpret the radiographs with respect to the electrodes, the device and changes in heart configuration. Major migration of electrodes is visible, but the detection of little changes in configuration is only possible with the help of serial radiographs. If extraperitoneal placement of the device is suspected, an ultrasound examination should be obtained. An important complication for the radiologist is a possible deactivation of some devices by electromagnetic interference.

Contraindications↗
PubMed1992

[Radiologic diagnosis before and after liver transplantation].

The main function of imaging procedures before liver transplantation is the exclusion of factors that may either constitute contraindications to surgery or necessitate a modification of the operation technique. Ultrasound and MRI are the modalities best suited for this purpose. After transplantation, imaging procedures are required mainly for diagnosis of and differentiation, in particular, between vascular and biliary complications, rejection, and infection, since these postoperative complications very often cannot be reliably differentiated on the basis of clinical and laboratory parameters alone. As vascular disturbances can vary widely in their presentation and can mimic other complications, duplex Doppler sonography plays a dominant role in clarification of the perfusion status of the graft. If infection is suspected, ultrasound generally has to be supplemented by other imaging procedures such as CT or MRI; if these techniques reveal suggestive lesions, a fine-needle aspiration is mandatory in most cases. Invasive procedures such as angiography or PTC are now applied only in selected cases, especially if an intervention is contemplated. Rejection cannot be reliably diagnosed by any of the imaging techniques and still requires biopsy.

Diagnostic Imaging↗
PubMed1991

[Digital radiography: optimization of chest radiographs using a modified exposure control].

Phototiming over the lung fields frequently compromises the signal-to-noise ratio available in the mediastinal and diaphragmatic regions of the chest. A moderate dose increase would be justified if a significant improvement in diagnostic performance could be achieved. We compared the impact of mediastinal phototiming (150 kVp, 150 cm FFD, 1.0 mm focus, 12:1 grid [higher kVp chosen to minimize dose increase]) to standard lungfield phototiming (125 kVp, 150 cm FFD, 1.0 mm focus, 12:1 grid) on the detectability of simulated pulmonary nodules (wax, 0.5-2.5 cm in diameter) superimposed on human volunteers in storage phosphor radiographs (1744 x 2144 pixels, 10 bit). ROC analysis of 1920 observations by 8 readers showed a significantly higher (p less than 0.03) detectability of simulated pulmonary nodules with mediastinal phototiming (ROC area = 0.89) than standard lungfield phototiming (ROC area = 0.84).

Humans↗
PubMed1991

[Postoperative conventional tomography of the temporal bone in the assessment of inadequate perception in patients with cochlear implants].

Between August 1984 and August 1990, 166 patients received a 22-channel cochlear implant (Nucleus) in the ENT clinic in Hannover. Some of these patients who were able to understand speech nevertheless complained of inadequate perception. To study this further a phantom skull with a cochlear implant was examined by CT and by conventional tomography of the petrous bone in various image planes. The method of choice for evaluating the position and appearance of the cochlear implant proved to be conventional tomography of the petrous bone in the frontal transorbital plane. In 7/23 patients examined it was possible to demonstrate dislocation of the electrodes; this is evidently responsible for the faulty perception.

Adolescent↗
PubMed1991

Hardware and software artifacts in storage phosphor radiography.

Hardware and software artifacts in digital radiographs acquired with storage phosphor systems can seriously impair image quality and imitate or mask abnormalities. These artifacts are caused by image plate, image reader, and laser printer defects; faulty image readout; processing errors; and unsharp masking. The artifacts can simulate calcifications and pneumothoraces or conceal low-contrast ill-defined lesions and subtle lesions along opacity interfaces. Hardware artifacts need to be recognized and properly traced to repair the system or improve its maintenance. Artifacts due to software characteristics and image post-processing must also be identified to ensure adequate system handling and adjustment of postprocessing algorithms.

Artifacts↗
PubMed1991

[Digital projection radiography].

Several hundred storage phosphor digital projection radiography (DR) systems are in operation in many parts of the world in experimental and clinical settings. They are used clinically for almost all projection radiographic studies except mammography. An overview is given of the experimental and clinical results achieved so far. Image post-processing has yet to meet the initial expectations. The average image quality will certainly improve with automatic brightness control. Edge enhancement should be performed in selected applications only. A true increase in diagnostic information probably cannot be expected except with dual energy techniques. Dose reductions are possible only in those studies in which the specific imaging task permits a decrease in signal-to-noise ratio.

Humans↗
PubMed1991

[Destructive non-infectious spondylopathy during hemodialysis].

Improvement of long-term treatment with hemodialysis requires an optimized radiological differential diagnosis of bone changes associated with long-term hemodialysis. 85 patients with chronic renal failure on maintenance hemodialysis were examined. In a conventional radiographic skeletal survey of the whole spine, 22 patients (26%) had involved intervertebral discs. The site of predilection was the cervical spine followed by the lumbar spine; oligosegmental involvement was seen in nine patients. Eighteen patients with destructive non-infectious spondyloarthropahy had juxtaarticular cystic bony changes associated with the hip, shoulder and wrist. Bone biopsy in eight patients revealed amyloid as content of these cysts. The interrelation between the duration of preterminal and terminal renal failure on one hand and destructive bone changes in the spine and cysts on the other hand seems to point to destructive spondyloarthropathy as an important complication of renal insufficiency and dialysis.

Adult↗
PubMed1991

[Complications of osteosynthesis in the x-ray picture].

Internal and external fixation devices are widely used in traumatology and orthopedic surgery. Early radiographic detection of complications due to bone surgery is based on a thorough knowledge of the different types of implants and their biomechanical properties. The development of early and late complications is demonstrated.

Equipment Failure↗
PubMed1990

[Ultrasonic evaluation of homologous bone and cartilage transplants of the femoral condyles].

Evaluation of the weight-bearing articular cartilage of the femoral condyles is possible by sonography. Bone and cartilage transplants can be examined by conventional radiological methods combined with sonography. This provides clinically relevant information. Sonography is a cheap imaging method for providing additional information on the post-operative course of cartilage transplants.

Adult↗
PubMed1990

[Postoperative diagnosis following separate replacement of an aortic valve and an ascending aorta using IV-DSA and CT].

We performed a follow-up examination by intravenous DSA and dynamic CT of 14 patients with separate replacement of aortic valve and ascending aorta due to an aneurysm or an aortic dissection. In 5 patients, we found an aortic ectasia at the aortic bulb or a perfused "graft inclusion". Both are best demonstrated with dynamic CT. As a result of the study, the operation technique was changed. In the postoperative management of patients with separate replacement of aortic bulb and ascending aorta, careful monitoring by dynamic CT is necessary even in the absence of clinical symptoms.

Adult↗
PubMed1990

Storage phosphor versus screen-film radiography: effect of varying exposure parameters and unsharp mask filtering on the detectability of cortical bone defects.

Diagnostic performance with storage phosphor radiography is influenced by exposure parameters and digital filtering algorithms. The authors compared the detectability of cortical lesions in excised human femoral shafts on state-of-the-art screen-film radiographs and storage phosphor digital radiographs. For the digital system, the effect of varying exposure parameters (photon flux and tube voltage) and unsharp mask filtering (kernel size and enhancement factor) was tested. Analysis of receiver operating characteristics was performed for 10,560 observations made by eight radiologists. Under identical exposure conditions, storage phosphor imaging yielded no significant advantages over conventional screen-film radiography. Although large variations in exposure dose are possible with storage phosphors, the potential for dose reduction was limited even by means of an increase in tube voltage. The performance with unsharp masked images declined with decreasing kernel size and pronounced enhancement.

Bone and Bones↗
PubMed1990

[Sonography of the wrist and the hand].

Sonographic examination of the hand requires high-frequency linear transducers. As the relevant structures are located very close to the surface, water stand-off pads are mandatory. Owing to the high sensitivity of sonography in the detection of fluid, exudative synovitis, tenosynovitis and ganglia can be easily diagnosed. Sonographic information on muscle atrophy and alterations of the shape and echogenicity of the median nerve in patients with carpal tunnel syndrome may be useful in evaluating the extent of disease. Further indications for the sonographic examination of the hand include suspected tumors, foreign bodies and synovial proliferation. Osseous destruction can be visualized in patients with rheumatoid disease, but the precise extent is hard to determine.

Arthritis↗